New Geochemical and Geophysical Data from the Western...
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Evan Twelker and Laurel Burns Alaska Division of Geological & Geophysical Surveys NEW GEOCHEMICAL AND GEOPHYSICAL DATA FROM THE WESTERN WRANGELLIA MINERALS ASSESSMENT AREA Alaska Miners Association 24 th Biennial Mining Conference April 7-13, 2014 – Fairbanks, Alaska
Transcript of New Geochemical and Geophysical Data from the Western...
Evan Twelker and Laurel Burns Alaska Division of Geological & Geophysical Surveys
NEW GEOCHEMICAL AND GEOPHYSICAL DATA FROM THE WESTERN WRANGELLIA MINERALS
ASSESSMENT AREA
Alaska Miners Association 24th Biennial Mining Conference April 7-13, 2014 – Fairbanks, Alaska
Presenter
Presentation Notes
The Alaska Division of Geological and Geophysical Surveys (DGGS) Wrangellia Project is a multi-year effort to improve our understanding of the Wrangellia geologic terrane and its potential to host deposits of the strategic and critical platinum group elements, or “PGEs”. I’ll give a brief project background and then present our geochemical and geological results and offer some context and preliminary interpretations, and then I’ll hand the podium over to Laurel Burns who will do the same with the results of the geophysical survey.
Acknowledgements Funded by the Legislature as part of the Governor’s
Strategic and Critical Minerals Assessment Capital Improvement Project which supplements the ongoing Airborne Geophysical/Geological Mineral Inventory
The crew: Rainer Newberry, Larry Freeman, Karri Sicard, Erik Bachmann, David Reioux, Colby Wright, Amy Tuzzolino
Alicja Wypych – petrologist/geochemist new at DGGS Gina Graham – geophysicist at DGGS Ken Severin and the UAF AIL Jon Findlay and the Pure Nickel crew Phil St. George and Millrock Resources The Prophecy Platinum crew at Wellgreen The USGS, USBM/BLM, and explorationists who have been
building the Wrangellia Ni-Cu-PGE story over the years
Presenter
Presentation Notes
We would like to acknowledge the many people and organizations that have helped us on this project.
Why are we interested in PGEs?
Strategic & Critical Minerals PGEs essential as catalysts Automotive Chemical industry Your new EPA woodstove
Heavy dependence on foreign sources: US Net import reliance: 91% of Pt, 56% of Pd1
Mine production: South Africa + Russia = 92% of Pt, 77% of Pd1
1USGS 2013 Commodity summary for Platinum-Group Metals
(PGEs = Platinum-group elements: Pt, Pd, Rh, Ir, Os, Ru)
Crimean Crisis
Presenter
Presentation Notes
PGEs are classic examples of critical minerals: 1) they have a central role in modern technology – motor vehicles, petrochemical and fertilizer refining, and 2) supplies could be at risk in the event of conflict, foreign political events, natural disaster, etc. The vast majority of the supply comes from South Africa and Russia. The #3 PGE producer is Zimbabwe. The Stillwater Mine in Montana produces PGEs, particularly Pd, but it is the only domestic producer. Despite this, the US imports the majority of its Pd from Russia.
Where are we going to find PGEs in Alaska?
Fairbanks
Anchorage
Project Area
Terrane map modified from Colpron and Nelson, 2011
Wellgreen 2B lbs Cu 2B lbs Ni 133m lbs Co 2.4M oz Pt 3.3M oz Pd*
MAN Project
Kennecott
Caribou Dome Farewell Project
Farewell Geophysical Survey
*Life-of-mine production under 2012 PEA (Tetra Tech Wardrop, 2012)
Presenter
Presentation Notes
Alaska hosts a variety of PGE prospects, including mineralization associated with Ural-Alaska type intrusions in Southeast and Southwest Alaska. However, some of the most prospective hunting ground is the Wrangellia Composite Terrane and its associated Late Triassic mafic-ultramafic intrusions. The Wrangellia Composite Terrane is a suite of Paleozoic arc volcanic and sedimentary rocks, a thick, Late Triassic oceanic flood basalt known as the Nikolai Greenstone (dark purple); and overlying Late Triassic limestones. It is tectonically dismembered and stretches through Central and Southeast Alaska, the Yukon, BC, and into Washington and Oregon. Just over the border in the Yukon, a differentiated mafic-ultramafic feeder to the Nikolai Greenstone hosts the Wellgreen Ni-Cu-PGE deposit. This is a magmatic type deposit with some similarities to the Norilsk deposit in Russia. It is a past-producing mine that is presently being explored and evaluated as an open pit by Prophecy Platinum. It’s a significant PGE resource, and a good analogue for what we might explore for in Alaska. In the Paxson area, the MAN Project is starting to put together a body of Ni-Cu-PGE mineralization hosted in Late Triassic intrusions. Further, the Farewell area in the Western Alaska Range has some similar style PGE mineralization, also hosted by Late Triassic mafic-ultramafic sills. The DGGS’s Farewell Geophysical Survey was flown last summer and should be released shortly. Finally, Wrangellia hosts some other really interesting mineral deposits, including the famous high grade Kennecott copper deposits, and in the project area, the Caribou Dome copper prospect. These appear to share a genetic link to the Late Triassic magmatic episode via their association with the copper-enriched Nikolai Greenstone.
Project overview
1. New airborne magnetic and electromagnetic data 2. Geologic/geochemical evaluation of Ni-Cu-PGE potential 3. Reanalysis of existing pulps with modern techniques
~1600 USGS stream sediment re-analyses by June 30
Presenter
Presentation Notes
The DGGS is building our understanding of Wrangellia’s PGE potential with three different initiatives. First of all, we contracted an airborne geophysical survey over un-surveyed areas with prospective geology. This was flown last summer and the dataset was released in January. Second, the Minerals Section field crew spent a few weeks sampling and mapping across the project area. We’ll continue our work in the area with a mapping project this coming field season. Finally, Melanie Werdon and David Reioux have been working to bring historic USGS and USBM data into the digital age, and there are currently about 1600 USGS AMRAP stream sediment pulps getting modern re-analyses as part of a DGGS-USGS cooperative agreement. These results should be released by the end of June.
Geological/Geochemical Program Rock samples for multi-element and
PGE analysis, lithogeochemistry 137 stream sediment samples
for multielement geochemistry indicator mineralogy
Magnetic susceptibility Gravity profiles (39km) Petrologic and
stratigraphic studies
Rock sample Stream sed Gravity profile
Presenter
Presentation Notes
This slide illustrates the area covered by the 2013 program of targeted geologic mapping and sampling, stream sediment sampling, and gravity surveying. We worked from east to west, building our understanding in the more studied part of the project area before moving on to the less studied, less explored southwestern half. Our sampling and mapping targeted known and suspected Late Triassic mafic-ultramafic intrusions inferred from previous mapping, geochemistry, and geophysics.
Cu
Copper: Basaltic Cu Skarn Ni-Cu-PGE
z = value - mean std dev
“anomaly map” (no economic
threshold implied)
Log transformed
3.82 % Cu 24 g/t Ag (Skarn)
4.19 % Cu 21 g/t Ag (Basalt)
1.94 % Cu 2.5 % Ni 0.06 % Co 395 ppb Pt 706 ppb Pd (Magmatic sulfide)
9.8 % Cu 22.6 g/t Au 104 g/t Ag (Skarn)
Data released on April 9th as RDF 2014-3: http://www.dggs.alaska.gov/pubs/id/27181
Presenter
Presentation Notes
To summarize geochemical results I’m going to present a series of maps, but first let me a say a few words about what these represent. These are anomaly maps. First, because the data most closely approximate a lognormal distribution I’ve done a log transformation. Next, I’ve calculated the z-score: the value minus the mean all divided by the standard deviation. This gives results in terms of “standard deviations above or below the mean”. No economic significance is implied, but it gives you a pretty clear and objective picture of the geochemical picture shown by our sampling. It also makes it easier to compare rock samples, stream sediments, and panned concentrates, which are plotted as triangles, circles, and hexagons respectively. I’ve labeled some rock sample highlights with absolute concentrations. You can see a cluster of high copper values in the Maclaren drainage, Windy Creek, and the northeastern Watana Mountains. These anomalies reflect skarn mineralization associated with poorly constrained, possibly Cretaceous intrusions; basaltic-Cu mineralization hosted by the Nikolai Greenstone or adjacent sediments, and also magmatic sulfide occurrences such as in the Canwell Glacier area. These data were released April 9th, 2014 as RDF 2014-3 (Twelker et al, 2014).
Cu
Ag Basalt-hosted Copper ARDF Sites ( )
Copper: Basaltic Cu Skarn Ni-Cu-PGE
z = value - mean std dev
“anomaly map” (no economic
threshold implied)
Log transformed
Presenter
Presentation Notes
As you can see, there’s a pretty good spatial correlation with the distribution of Ag, and there’s a pretty good spatial correlation with the distribution of copper, even skarn copper, with the distribution of basaltic copper type ARDF sites.
Au
Intrusion-related systems
1.29 g/t Au
3.84 g/t Au
15.35 g/t Au
22.6 g/t Au
Presenter
Presentation Notes
Similar patterns are apparent for the distribution of gold. Gold-rich rock samples come from skarn and Nikolai Greenstone-hosted veins and disseminations. Many of these samples show a strong Cu-Ag association.
Au
Intrusion-related systems
As
Bi
W
Presenter
Presentation Notes
The distribution of Au in the study area is mirrored by a variety of other elements which are generally associated with intrusion-related Au systems.
Magmatic System: Ni-Cu-Co-PGE
Pt
28 ppb Pt 73 ppb Pd
69 ppb Pt 57 ppb Pd
1090 ppb Pt 1130 ppb Pd
1270 ppb Pt 1450 ppb Pd
Presenter
Presentation Notes
Elevated Pt values cluster mainly around known prospects in the Eureka Creek and Canwell Glacier areas, but with an additional anomalous cluster in the Watana Mountains (the northeastern Talkeetna Mountains)
Magmatic System: Ni-Cu-Co-PGE
Pt
Pd
Co
Ni Cr
Presenter
Presentation Notes
Pd (and Co) anomalies share a close spatial relationship to the Pt anomalies, as does Ni. Ni anomalies may be sourced from Ni sulfide or from olivine. Chromium, on the other hand, isn’t part of sulfide mineralization. In general terms, Cr maps the distribution of ultramafic rocks. The close coincidence of PGE, Co, and Ni anomalies with the distribution of Cr reflects the ultramafic host rocks.
Mafic-Ultramafic intrusions Normative mineralogy; DGGS & USGS data
Gabbro, gabbronorite, olivine gabbro
Olivine gabbro
Gabbroic: troctolite, olivine gabbro Ultramafics: harzburgite, dunite
Plagioclase
Pyroxene Olivine
Emerick, Canwell Glacier
Alpha Complex
Peak 5532
Presenter
Presentation Notes
We have used our whole rock geochemical results to calculate the CIPW normative mineralogy of mafic and ultramafic intrusive rocks from our fieldwork this summer. I augmented our data with previously collected DGGS Iron Creek data (Werdon et al, 2000) and USGS Talkeetna Mountains Transect analyses (Alaska Geochemical Database; Granitto et al, 2011). A simple plot of plagioclase, olivine, and pyroxene reveals three basic groups: 1) gabbros and gabbronorites, with some olivine gabbro; 2) pyroxene cumulate(?) olivine gabbro; and 3) olivine cumulate rocks including troctolite, olivine gabbro, harzburgite, and dunite. The olivine (+/- pyroxene) cumulates are associated with known mineralization at Emerick, Canwell Glacier, and the Alpha and Rainy complexes in the western part of the study area; additional olivine-rich rocks are found in two clusters in the NE Talkeetna Mountains. These include the Peak 5523 area, featured in the next several slides.
Peak 5532 Gabbroic Complex
Presenter
Presentation Notes
This oblique photo shows an example of field observations. The reconnaissance nature the existing geologic maps means that there are unmapped PGE-prospective mafic-ultramafic intrusions in the project area. Most of the exposure pictured here was previously mapped as Paleozoic sediments. Numerous leucogabbro bands are clearly visible in the outcrop; petrologic dissimilarity and rare discordant contact relationships suggest that these are late dikes rather than magmatic layers.
Peak 5532: Cross Section
Based on measured dips, approximately 700 m (2300 feet) thick
Presenter
Presentation Notes
This is a cross section based on mapping and sampling stations projected to a NW-SE section running through Peak 5532. Measured dips of hanging wall and footwall hornfels bedding suggest that the body dips about 35 degrees to the SE and has a sill-form, semi-conformable attitude.
Peak 5532: Modal Zonation
General pattern of more mafic, more olivine towards center of the most mafic phase of the complex
Presenter
Presentation Notes
The sill is apparently multi-phase, with a more orthopyroxene-rich upper phase occupying the top of the hill, and a lower olivine gabbro to olivine-rich troctolite phase occupying the lower portion. The lower phase appears to become increasingly mafic towards its center.
Ni-Cu-PGE deposit-forming processes
Volcanic Pile
Diagram modified from Arndt et al, 2005
Pyritic seds (sulfur source)
The Mantle: Elevated PGEs
Two Challenges:
1) Extract magma from the mantle without losing the Ni-Cu-PGE
2) Concentrate the Ni-Cu-PGE as high grade ores
Near surface, i.e. accessible to mining
Presenter
Presentation Notes
I’d like to dig a little deeper into the magmatic processes that control the PGE potential in the project area, but before I do that I’ll offer a brief overview of the magmatic type Ni-Cu-PGE model. A fundament al issue is that Ni, Cu, and the PGEs are concentrated mostly in the core and mantle. They partition into sulfide minerals and sulfide melts, and nickel may also partition into olivine. From an economic standpoint, we face two challenges. Mantle melts and their associated metals have to be extracted from the mantle and transported all the way to the upper levels of the crust WITHOUT losing the metals, and The metals have to concentrate as ores once they reach the crust
Ni-Cu-PGE deposit-forming processes
A B C
Volcanic Pile
Diagram modified from Arndt et al, 2005
Pyritic seds (sulfur source)
Scenarios: A. Sulfide saturation at a
deep level: PGE, Cu, Ni not extracted with melt
B. Olivine saturation at a deep level: Ni not extracted
C. Sulfide, olivine are undersaturated until high level emplacement: Sulfide melt can separate, interact, and accumulate in economic quantities
Presenter
Presentation Notes
There are several scenarios that could play out: Sulfide-saturation is reached at some point early in the magma’s ascent, the sulfide melt separates out, and the associated metals are not emplaced at a minable depth. Olivine crystallizes early on, at a deep level, and the Ni is not extracted. If everything is in our favor, sulfide and olivine will not separate until a high level. At Norilsk, sulfide saturation and separation is thought to have been driven by assimilation of sulphur-rich evaporite beds. At Wellgreen, pyritic sediments apparently contributed sulfur and caused sulfide separation. Once sulfide melt separates, the key is for is it to concentrate into ore grades. Here, gravity separation plays a major role, and often the deposits will be found at ‘riffles’ or other collection points at the bottom of mineralized intrusions.
Peak 5532: Olivine Compositions
‘Normal’ olivine
Ni-depleted olivine
Yukon data from Hulbert, 1997
Microprobe data (WDS) collected at UAF’s Advanced Instrumentation Laboratory
Presenter
Presentation Notes
Taking these concepts to the study area, we’ve used the new UAF microprobe to collect data on the Ni content of olivine. While the margins of the Peak 5532 complex seem to have normal, Ni-rich olivine compositions, the more mafic center of the intrusion has Ni-depleted compositions similar to those seen at the Wellgreen deposit and the Emerick prospect (13RN411C). This suggests that a Ni-bearing sulfide melt separated from the magma prior to crystallization of olivine in the central part of the intrusion.
Peak 5532: Magmatic Fe-Ni Sulfides
olivine
plagioclase
pyrrhotite/ pentlandite
olivine
cpx
pyrrhotite
magnetite
pentlandite
BSE images
Presenter
Presentation Notes
We can see concrete evidence for this under the microprobe. Here is a backscatter electron image showing an interstitial magmatic sulfide grain in a sample of olivine-rich troctolite. On closer inspection you would see that this grain is a composite of pyrrhotite and the Ni-Fe sulfide pentlandite. Here’s another image showing an inclusion of magmatic sulfide in olivine—good evidence that the sulfide liquid separated prior to olivine crystallization. If you zoom in on the inclusion you can see that it’s comprised of exsolved pyrrhotite and pentlandite, with a bit of magnetite around the edges. We identified the minerals using quantitative electron-dispersive spectroscopy. First-pass work also showed that, as expected, the magmatic sulfide contains copper and cobalt.
Pt
PGE content of sulfide
Pd
Concentrations in 100% sulfide*
Wellgreen data: Hulbert (1997); BLM data are from Bittenbender et al (2007)
DGGS sample
BLM sample
Disregards variable sulfide concentrations, focuses on magmatic system processes (no relation to economics)
High values imply a high degree of sulfide-silicate melt interaction
Comparable values to Wellgreen deposit, YT Norilsk, Russia
Much less than Stillwater J-M
*sulfide calculated using 35.7% S
Presenter
Presentation Notes
We were not able to identify any PGE bearing phases under the microprobe, but by knowing the whole-rock sulfur and PGE content we can calculate the approximate PGE content of the sulfide. For the purposes of comparison I’ve incorporated the BLMs extensive geochemical sampling. When you look at the sulfide PGE content you can see that the values in the Canwell Glacier, the Alpha Complex, and the Peak 5532 in the northeastern Talkeetna Mountains are relatively enriched, with values similar to those published for the Wellgreen deposit in the Yukon. Even though some of the intrusions arguably resemble layered mafic intrusions, these values are orders of magnitude lower than those found at the Stillwater J-M reef. In summary, it looks like there are good geological similarities between the study area and the Yukon analogues. While economic accumulations of magmatic sulfide may not have been found yet, it looks like some of prerequisite magmatic processes have occurred. It may simply be a question of finding the spot where magmatic sulfide has a chance to physically separate and accumulate.
Stay Tuned: 2014 STATEMAP Project: Talkeetna Mountains C-4
• 1:50,000 • Bedrock & surficial maps • Structural history • Ni-Cu-PGE potential • USGS STATEMAP matching grant
Fog Lakes Graben
Talkeetna
Anchorage
C-4
Geology after Wilson and others, 1998
Presenter
Presentation Notes
Finally, we’re going to continue working in Wrangellia this coming summer, this time in the central Talkeetna Mountains. Our proposed Talkeetna Mountains C-4 mapping project has been approved for USGS STATEMAP matching funding. A couple of the reasons this map area is a good choice: The potential for magmatic Ni-Cu-PGE deposits is poorly understood, but the area is being actively explored by MMG Exploration USA. Epithermal style Au mineralization occurs in association with intrusions related to the Tertiary volcanics. Finally, there is potential for basalt and sediment-hosted Cu related to the Nikolai greenstone. For all of these deposit types the critical geologic elements have not been mapped, even though they are known to be present in the area. The Fog Lakes graben extends through the northern part of the map area; if these faults are presently active they could present seismic hazard to the proposed Susitna-Watana Hydropower Project. This is a gap in the detailed geologic mapping and a place where the DGGS Minerals Section can make significant improvements to the geologic knowledge base.
Four Mag & EM Surveys
IRON CREEK
WRANGELLIA
SOUTHERN DELTA RIVER
VALDEZ CREEK
Wrangellia survey released January 2014 as GPR 2014-1 Online at: http://www.dggs.alaska.gov/pubs/id/27022
Presenter
Presentation Notes
Part 2: Results and preliminary interpretations of the Wrangellia geophysical survey (Burns et al, 2014; GPR 2014-1) The Wrangellia survey connects three previously flown geophysical surveys: - Iron Creek (PDF 98-9): http://www.dggs.alaska.gov/pubs/id/1822 (DGGS Staff et al, 1998) - Valdez Creek (GPR 2004-3): http://www.dggs.alaska.gov/pubs/id/3337 (Burns et al, 2004) - Southern Delta River (GPR 2003-5): http://www.dggs.alaska.gov/pubs/id/2904 (Burns et al, 2003) All of these surveys used the DIGHEM helicopter-borne magnetic and electromagnetic system. These surveys will ultimately be merged and re-release as a single map.
Geophysics Outlines Healy
Talkeetna Mts
Mt Hayes
WRANGELLIA
SDR
Presenter
Presentation Notes
The next series of slides will focus on the northeastern portion of the Wrangellia survey adjacent to the Southern Delta River survey.
“Major” Mapped Faults
DENALI
“TALKEETNA THRUST”
“A FAULT”
Presenter
Presentation Notes
This area is cut by major faults, including structures parallel and conjugate to the Denali Fault. Faults are from the digital data files of Wilson et al (1998).
NE area Magnetics High values
Low values
Presenter
Presentation Notes
This map shows the merged residual magnetic field product of the Wrangellia and Southern Delta River surveys.
NE area Magnetics High values
Low values
Presenter
Presentation Notes
The same map with major structures overlaid. An unmapped suspect fault (dashed black line) is apparent from the magnetic survey.
NE area Shadow Mag High values
Low values
Presenter
Presentation Notes
This structure (white line) is more clearly visible in a color shadow view of the residual magnetic field. Offset north-south trending magnetic features suggest right-lateral apparent displacement.
Analytic Signal High values
Low values
Presenter
Presentation Notes
This map shows the analytic signal of the magnetics. This product is insensitive to possible negative remnant magnetization in some rock units. A chain of highs (indicated by yellow arrows) corresponds to a belt of mafic to ultramafic rocks south of Butte Creek in the northeastern Talkeetna Mountains. These include the Peak 5532 gabbroic complex discussed previously in this presentation. This product also highlights some previously unmapped northwesterly-trending faults, shown in white.
Color Shadow Magnetics
Residual Magnetic field in 3-D
High values
Low values
nT
Presenter
Presentation Notes
This map shows a color shadow representation of the residual magnetic field product.
Color Shadow Magnetics High values
Low values
nT
Presenter
Presentation Notes
The next slide will zoom in on the yellow box.
Color Shadow
Magnetics
High values
Low values
Presenter
Presentation Notes
Color shadow representation of the residual magnetic field: The Wrangellia survey shows many apparent fault offsets of the magnetic Nikolai Greenstone unit; many of these are not captured on the existing geologic maps.
Detailed and Regional Magnetics
nT
Iron Creek not merged
Valdez Creek not shown High values
Low values
Presenter
Presentation Notes
This final map shows the merged Wrangellia and Southern Delta River surveys, as well as the Iron Creek Survey, in the context of the regional magnetic map.
References Cited Arndt, N.T., Lesher, C.M., Czamanske, G.K., 2005, Mantle-Derived Magmas and Magmatic Ni-Cu-(PGE) Deposits, in: Hedenquist, J.W., Thompson,
J.F.H., Goldfarb, R.J., Richards, J.P. eds., Economic Geology One Hundredth Anniversary Volume 1905-2005: Society of Economic Geologists, p. 5-23.
Bittenbender, P.E., Bean, K.W., Kurtak, J.M., Deininger, J., 2007, Mineral Assessment of the Delta River Mining District Area, East-central Alaska: BLM Alaska Technical Report 57, 697p.
Burns, L.E., CGG, and Fugro GeoServices, Inc., 2014, Wrangellia survey area: Airborne magnetic and electromagnetic data in line (point), grid, vector, and map formats, Talkeetna Mountains, Healy, and Mt. Hayes quadrangles, south-central Alaska: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2014-1, 56 sheets, 1 DVD, scale 1:63,360. Available online at: http://www.dggs.alaska.gov/pubs/id/27022
Burns, L.E., U.S. Bureau of Land Management, Fugro Airborne Surveys, and Stevens Exploration Management Corp., 2003, Plot files of the airborne geophysical survey data of the southern Delta River area, east-central Alaska: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2003-5, 1 DVD. Available online at: http://www.dggs.alaska.gov/pubs/id/2904
Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2004, Line, gridded, and vector data, and selected plot files of the airborne geophysical survey data of the Valdez Creek mining district, central Alaska: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2004-3, 1 DVD. Available online at: http://www.dggs.alaska.gov/pubs/id/3337
Colpron, M., and Nelson, J.L., 2011, A digital atlas of terranes for the Northern Cordillera: British Columbia Ministry of Energy, Mines, and Petroleum Resources, GeoFile 2011-11, http://www.empr. gov.bc.ca/ Mining/ Geoscience/ PublicationsCatalogue/ GeoFiles/ Pages/2011-11.aspx
DGGS Staff, Dighem, and WGM, Inc., 1998, CD-ROM containing profile and gridded data and section lines of the 1997 geophysical survey data for Iron Creek area, Talkeetna Mountains Quadrangle, southcentral Alaska: Alaska Division of Geological & Geophysical Surveys Public Data File 98-9, 1 DVD. Available online at: http://www.dggs.alaska.gov/pubs/id/1822
Granitto, M., Bailey, E.A., Schmidt, J.M., Shew, N.B., Gamble, B.M., Labay, K.A., 2011, Alaska Geochemical Database (AGDB)—Geochemical Data for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media: U.S. Geological Survey Data Series 237.
Hulbert, L.J., 1997, Geology and Metallogeny of the Kluane mafic-ultramafic belt, Yukon Territory, Canada—Eastern Wrangellia: A New Ni-Cu-PGE metallogenic terrane: Geological Survey of Canada Bulletin 506, 265 p.
Tetra Tech Wardrop, 2011, Wellgreen Project Preliminary Economic Assessment, Yukon, Canada. Report Prepared for Prophecy Platinum by Tetra Tech Wardrop, August 1, 2012.
Twelker, Evan, Bachmann, E.N., Freeman, L.K., Newberry, R.J., Reioux, D.A., Sicard, K.R., Tuzzolino, A.L., Wright, T.C., and Wypych, Alicja, 2014, Major-oxide, minor-oxide, and trace-element geochemical data from rocks and stream sediments in the Wrangellia mineral assessment area, Gulkana, Healy, Mount Hayes, and Talkeetna Mountains quadrangles, Alaska: Alaska Division of Geological & Geophysical Surveys Raw Data File 2014-3, 6 p. Available online at: http://www.dggs.alaska.gov/pubs/id/27181
United States Geological Survey, 2013, Mineral Commodity Summaries 2013: U.S. Geological Survey, Reston Virginia. 198p. Werdon, M.B., Riehle, J.R., Schmidt, J.M., Newberry, R.J., and Pessel, G.H., 2000, Major oxide, minor oxide, trace element, and geochemical data
from rocks collected in the Iron Creek area, Talkeetna Mountains B-5 Quadrangle, Alaska in 1999: Alaska Division of Geological & Geophysical Surveys Raw Data File 2000-2, 31 p., 2 sheets, scale 1:63,360
Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133-A, 62 p., 3 sheets.
